10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Evaluation of a Low-Cost Personal Sampler for Assessing Respirable Dust Exposure in Taconite Mining
REBECCA FOOS, Nima Afshar-Mohajer, Karl Braun, Gurumurthy Ramachandran, John Volckens, Colorado State University
Abstract Number: 1660 Working Group: Low-Cost and Portable Sensors
Abstract There have been significant advances in low-cost technologies for air sampling in recent years. Among the samplers currently being introduced to the market is the Ultrasonic Personal Aerosol Sampler, or UPAS (Volckens et. al. 2017). Several inlets have been developed for the UPAS to sample the fine particulate matter (PM2.5), inhalable particulate matter, and now the respirable fraction. A rigorous test of UPAS fitted with the respirable cyclone inlet in the field was lacking.
A taconite mining facility was selected as a suitable test location for evaluation of the respirable sampler performance. Beyond crude-ore extraction, taconite ore processing involves multiple stages of crushing, refining, and pelletizing to render a kiln-fired iron pellet ready for manufacturing. Each stage is characterized by unique aerosol profiles due to varied application of mechanical force and variable levels of water within the product. Representative employees from each production area volunteered to carry out personal collocations of the UPAS sampler with respirable cyclone and a traditional sampling pump with aluminum respirable cyclone. Participation requirements were limited to shift length alone, and partial shifts of fewer than eight hours were not sampled.
One hundred employees participated in the collocated deployment over the course of eight days. Pre-weighed filters were loaded into the respective UPAS cartridges and three-piece cyclone cassettes, and the UPAS and aluminum cyclone inlets were mounted in close proximity within the breathing zone of each participant and at the designed flow rates of 2.0 and 2.5 liters per minute respectively. Sampling duration varied between seven and twelve hours per the length of the employee shift. Following the field deployment, all filters were weighed again to determine the loaded filter weight.
Of the one hundred collocations, six were removed from the resulting data set due sampling error such as pump malfunction. The remaining ninety-four sets of filters were incorporated into the analysis. Total respirable mass was considered the primary metric. Adjusted for total volume sampled, the UPAS and traditional respirable samplers showed good agreement for total respirable particulate. Additional speciated analysis for various metallic elements as well as respirable crystalline silica is ongoing.
In conclusion, the occupational environment proved to be suitably rigorous, as demonstrated by the maximum filter loading and occupational exposure measured by the deployment. In such a heavy industrial setting, the Ultrasonic Personal Aerosol Sampler performed comparably to the traditional sampling train when sampling for the respirable fraction.
References J. Volckens, C. Quinn, D. Leith, J. Mehaffy, C. S. Henry, D. Miller-Lionberg, Development and evaluation of an ultrasonic personal aerosol sampler, Indoor Air, 2017;27: 409–416.